Highs and Lows
by whitchry9
Summary: Life with Sherlock was never boring, but that also means it was never easy. Especially when unforeseeable circumstances arose. 8 chapters.
1. Chapter 1

Sherlock eyed John.

He was sleeping. Again. Normally John slept a lot, at least by Sherlock's standards, which meant every night for at least a couple of hours, which Sherlock deemed excessive, but this? It was mid afternoon and John had managed to fall asleep on the couch while watching a new episode of Doctor Who. Very much out of character and very much not right.

And it wasn't that he hadn't gotten enough sleep last night, because he had, going to bed at a ridiculously early hour instead of helping Sherlock with his new experiment, and hadn't gotten up till after eight, when Sherlock played chromatic scales, loudly without stopping. John had already slept through the nicer pieces, and frankly Sherlock was getting fed up with waiting for John to come down and make tea for him.

"John," he called. "Wake up." He barely stirred. It would probably be cruel to fire the gun now, Sherlock figured. Same for an explosion.

"John," he called louder. John stirred slightly, but still not enough. Sherlock sighed loudly, hoping it would help. It really didn't.

"JOHN!" he bellowed. He thought it would get more of a reaction out of him, but he only startled slightly and cracked open his eyes.

"Mmm... what?"

"Get up," he demanded. "You fell asleep in the chair."

"Did it never occur to you to just let me sleep?"John protested.

Sherlock cocked his head. Oh. "Dull," he declared.

"Has it ever occurred to you that I don't exist purely for your entertainment? Because I'm exhausted and thirsty, and I really just want to sleep. And you go waking me up..." John trailed off and groaned. Sherlock eyed him suspiciously. It was like one of those times he realized he wasn't going to get any sleep that night because he'd be busy digging glass out of Sherlock's wound, or keeping him awake because of a concussion. Except this time, Sherlock hadn't done anything. (That he knew of.) Or one of those times when he realized he was chasing after a bloody murderer with nothing but a handgun and Sherlock's wits. Or that he'd just texted a murderer. Or that he'd woken up after falling off a building with a murderer.

John seemed to groan a lot when there were murderers involved. Sherlock made a note of that to study for later.

But there were no murderers now, because Sherlock wasn't even on a case. So Sherlock had to admit it, and hated it, he had no clue what was going on.

"What?" he asked, trying his best to sound uninterested.

"I'm going to the clinic," he replied, dragging himself out of his chair to, presumably, go get dressed. It was not like John to wear his pyjamas out.

Sherlock frowned. John wasn't working. Which meant he was sick. Except he didn't seem sick. Tired, yes, but not sick.

"Why?" he asked. If he kept this up he was going to go through all the questions.

"Blood test," he called as he headed up the stairs.

Sherlock frowned. He could test John's blood. What did he want it tested for?

Sherlock bounded up the stairs to find John shrugging on a jumper, jeans already on.

"What for?" At least that was a repeat of an earlier one.

"Sherlock," John said wearily, "I'm going to the clinic. Either you can come, or you can stay home and stop asking questions."

Sherlock pondered that. "Does that mean if I come, I can ask questions?"

John shook his head.

Sherlock sighed dramatically. "Well, I've got nothing else on today, so I suppose I could come along."

"Oh thank you," John muttered.

Sherlock frowned at him. "No need to be rude."

John rubbed his face with his hand. "Sorry. Tired. Go put pants on or you're not coming."

Sherlock glanced down. Sure enough, still in his pyjamas.

"Right."


	2. Chapter 2

Five minutes later they were both dressed and on their way to the clinic.

Ten minutes after that, John was greeting Sarah and Sherlock was pouting in a chair.

"I don't see why you have to wait like everyone else," Sherlock muttered as John sat down next to him. The waiting room was filled with sneezing and sniffling people of all ages. Sherlock loathed sick people. Except for John of course. He never loathed John.

"It's not urgent Sherlock. I can wait just fine. Besides, I told you that you didn't have to come."

Sherlock snorted. "Right, and wait for you to come home and not tell me anything."

John shrugged. "No complaining then."

Sherlock was silent for a minute, scanning the room.

"Bored," he declared.

John put down the magazine he was attempting to read, and failing. He groaned. "Sherlock, please."

Sherlock scanned the room again before pointing things out.

"The woman over there," he began, gesturing to one half of an elderly couple, "Is having an affair."

"No way..." John muttered.

Sherlock smirked at him.

"And that woman," he said, pointing to a woman who looked rather ill, almost green. "Is pregnant, but not with his child," he finished, pointing to the man next to him. "In fact," he continued, spying a man across the room, also sitting next to an ill looking woman. "He's the father. And she's pregnant too."

John looked impressed. "Is it his baby, or..." he gestured towards the other man.

Sherlock smirked. "Yes, it's probably his. But the one he's with is looking to get an abortion."

"And the other?"

"Doesn't know she's pregnant. Thinks it's the flu."

John snickered. "And the rest of them?"

"It is the flu. Or something else viral."

Sherlock rolled his eyes at the room in general.

"It's all viral," he declared loudly. Everyone turned to look at him, except for the elderly man. (Mostly deaf.)

"Excuse me?" a woman said, her daughter's head perched in her lap.

Sherlock scanned her. _Single mother, works full time as a secretary, her mother watches her child while she's at work, but she's got dementia that no one's noticed yet. The child's been getting into things that she hasn't noticed. _

"Paracetamol overdose for her."

"What?" she trilled.

"From your aging mother. She has dementia. Get her tested."

She gaped at him, but thankfully, she was called next. Or perhaps Sarah had taken pity on her. Either way, she left and Sherlock had to move on to the rest of the waiting room.

"Viral!" he declared once again.

"_Shut_ _up,"_ John hissed.

"Why?" he retorted.

"Sherlock," John hissed. "I will call Mrs Hudson right now and get her to dispose of whatever the hell that thing is that's on the counter growing mould!"

Sherlock's eyes narrowed. "You wouldn't dare."

"Oh yeah?" John smirked. "Try me."

Sherlock was silent after that, taking turns between glaring at people and loudly flipping through magazines.

Finally it was their turn, Sarah leading them to a room, John wishing he could sink into the ground as Sherlock trailed behind them, scowling and stomping like a five year old.


	3. Chapter 3

Sarah, _bless her heart_ thought John, ignored him entirely.

"What can I do for you John?"

John glanced at Sherlock, examining the cabinets of medical supplies, and made a note to pat him down before they left.

"Blood glucose, electrolytes, ketones."

She nodded. "Finger stick for the glucose or draw?"

"Both."

She set about gathering supplies, swatting Sherlock's hand away from cupboards like a child in a cookie jar. She returned with alcohol swabs, test strips, finger pokers, collection vials, needles, a tourniquet, an ancient blood glucose monitor, a urine collection bottle, and a set of gloves.

"Finger first, and then I'll get you to pee in the cup while the meter thinks about it."

John nodded, holding out his finger for Sarah to swab and poke, and barely blinked as she squeezed out a droplet that was big enough to sustain a vampire.

"Sorry," she said. "We really need to get new ones."

Sherlock stood over, watching, as Sarah stuck a plaster on John's finger and handed him the bottle. He smiled at her and trudged off to fill it up.

Sherlock came over to poke at the supplies still left out.

"What's that for?" he asked, poking his finger at the machine, which was counting down. Slowly.

Sarah swatted his hand away again.

"Stop touching or I will send you back to the waiting room. Sit," she ordered, pointing to the extra chair in the room. He obeyed.

John returned with the filled bottle, raising an eyebrow bemusedly at Sherlock.

"We'll send that off to the lab. Now sit yourself down and we'll draw some blood."

"Is the meter done?"

"Just finishing up... now."

"And?"

They could both tell by the look on her face. Sherlock wasn't sure what it meant, but it was one of those 'not good because I have to tell you bad news' looks.

"23.4."

John sat back in the chair dejectedly and held out his arm.

"Yeah, I expected that," he admitted.

Sarah nodded. "We'll just get another sample to send off to the lab and check the urine for ketones. And it'll be the hospital for you I'm afraid."

John smiled sadly. "No chance of doing it here on an outpatient basis? I know what to do and everything."

"We'll see," she replied, expertly threading the needle into his arm and drawing out two vials.

"Hold that there," she told him, exchanging her fingers for his on the gauze.

Sherlock looked between them blankly.

"What's going on?"

John grinned. "You haven't figured it out yet?"

Sherlock frowned. He hated when John didn't tell him things. It was the only reason why he came to the clinic with him. It certainly wasn't for the entertainment value, although he had to admit that was high.

"Tell me," he demanded.

They both ignored him.

"All the usual symptoms?" she asked.

John nodded, ticking them off on his fingers. "Increased thirst, urination, hunger, I've been tired, and probably some weight loss, although I haven't checked."

Now that Sherlock looked closely, he realized John was probably right. Why hadn't he noticed that?

"Then it's almost positive. This really warrants an admission you know."

"Can you just dip it for ketones? Any ketones and I'll go to the hospital, I promise," he pleaded, giving her his best wooing look.

Sherlock held back a snort.

But it worked.

"Trace. Not enough to warrant a hospital visit."

John smiled broadly. "The deal still stands then? Write me a script for strips and insulin, and I'll go home. Out patient consult tomorrow and everything."

Finally, _finally, _Sherlock got it.

"Diabetes mellitus," he announced proudly.

John slow clapped for him. Sherlock scowled.

"A bit old for that aren't you?" he scoffed.

"Never!" John declared.

Sherlock frowned. "That's another one of those movie references I don't get, isn't it?"

"If you'd watch them with me instead of moaning about me watching them..."

Sherlock dismissed him with a wave of his hand. "Dull. Can we go now?"

"No, not yet," Sarah interrupted. "I've got to write John some scripts, give him some information, and set up an appointment for him tomorrow with an endocrinologist."

"Dull," Sherlock sighed.

"There's really no need for you to accompany me to that," John reminded him.

Sherlock scoffed. "Of course there is. I have to be able to take care of you."

John blushed when Sarah smiled at them with The Smile. The one he hated.

"Shut up," he muttered.

"It's true," he told John, completely missing the point. "If you're sick or pass out or something, especially on a case, it will greatly impede my work."

"Right. The Work."

Sherlock frowned. John was mocking him. Wasn't he?

Sarah dug through drawers and gathered a stack of papers and pamphlets, all brightly coloured.

"Some reading material. Oh, don't do that," she scoffed, seeing John roll his eyes. "I know you know the theory, but it's always better to be safe. A sliding scale for food and dosing, as well as information about the long acting. I'll give you a shot and let you look this over while I call and make you an appointment."

She stood back and studied him. "You're left handed, so I'll give it to you in the left arm. You're less likely to do your own injections there, and you need to rotate your sites."

John nodded and rolled up his sleeve. Sarah swabbed him with an alcohol wipe and left him to dry while she drew up the needle.

"This should get you back down into just slightly above normal range, just to be safe. Don't want you passing out from hypoglycemia."

John nodded and looked away as Sarah injected the needle into his arm.

"All done," she stated. John rolled down his sleeve.

All the while, Sherlock just watched with fascination.

Sarah left the room with instructions for John to read the paperwork.

Sherlock noticed John looked... almost sad. Not quite though. Glum?

"You look... glum," he stated carefully, leaving room for John to correct him. He didn't.

"Well, I have just been diagnosed with a disease I'm going to have for the rest of my life. It tends to get you down a bit."

Sherlock nodded. He understood. Or he thought he did anyway.

"Why aren't you reading those. Sarah told you to read them."

John sighed. "Sherlock, I already know all this stuff. You can feel free to read it if you like."

Not even hesitating, Sherlock snatched the top couple of pamphlets from the stack and skimmed them. He tossed them back at John when he was done.

"You read them that fast?" he asked skeptically.

"Of course."

John rolled his eyes. "Should have suspected that I suppose."

"Yes, yes you should have," Sherlock replied, bored again. He examined the machine that Sarah had swatted his hand away from.

"I'll be getting one of those," John noted. "Much smaller and more efficient, but still..." he shrugged. "I'm sure there will be lots of room for experiments for you." He grinned, but it was more to make himself feel better than to reassure Sherlock who was fine, obviously. He was always fine.

Sarah returned with sheets of paper and a business card.

"Appointment tomorrow at ten thirty, and here are the scripts. Go fill them now. Sherlock, you make him do it. This is serious. You need to stay home with him tonight and not drag him off gallivanting somewhere."

Sherlock nodded, taking his duty seriously.

"Call me if there's anything else, or any questions."

"Thank you," John told her.

She grinned. "It's not often I get patients who come in knowing what they have. It's kind of nice for a change. Most of them have viral illnesses and still demand antibiotics."

Sherlock snorted. "Told you so," he muttered, nudging John.

John threw one last smile to Sarah and dragged Sherlock out by his sleeve.


	4. Chapter 4

They stopped at the chemist around the corner from their flat to fill the scripts Sarah had given him. John also picked up some other things that he didn't have a script for, but knew he would need, like glucose tabs and food.

Sherlock supposed the food would be good, considering what they had in their fridge was mostly limited to non edible experiments.

* * *

John dumped his supplies on the kitchen table when they got back, Sherlock marvelling at the goodies. John must have noticed the glint in his eye because he killed any plans before they even could develop.

"No touching anything. Not yet anyway. Got it Sherlock?"

Sherlock scowled, but nodded. It would be enough for now to learn.

He studied John's movement as he pulled a strip out of a container and stuck it in a meter similar to the one Sarah had, except as John had said, much smaller and more efficient. He watched as John diligently went through the process of checking to make sure the strips were good, testing with a control solution before pricking his own finger to squeeze out a drop of blood. Sherlock waited with bated breath as it counted down from five, and not the hundreds or so that the other meter had taken. John held it up for him to see when it was done.

"See, improving."

Sure enough, the number was now 16.4, a far cry from what it had been before.

"What's normal?"

John shrugged. "I'm not sure exactly, but around five."

Sherlock grabbed the pamphlets John had thrown on the table along with everything else and skimmed them.

"4.4 to 6.1," he declared.

John nodded. "Still a ways to go, but headed in the right direction. I'll check it again before I go to bed."

Sherlock frowned. "How often are you going to have to do that?"

John shrugged. "It really depends. At least three times a day. Before I eat, before I go to bed, before I go on a ridiculous chase with you, any time I feel funny. I can't say."

Sherlock sat back, pondering that.

"You know, this is seriously going to interfere with my work," Sherlock sighed.

John snorted. "Right. That's what I was worried about."

They spent the rest of the evening lounging around, watching crap telly and doing research, more on Sherlock's part than John. John was content to just watch telly, leaving Sherlock scouring the net for different treatments and technologies for diabetes. He was extremely disappointed that there was no cure, and made a note to bother Mycroft about that next time he 'stopped by', which was probably going to be as soon as he heard the news.

* * *

John went to bed early, still tired, and Sherlock scrutinized him as he tested again, repeating the same process as before.

"13.9," he informed Sherlock, like he couldn't read it himself. "Getting there." He pushed back from the table with a yawn. "I'm going to bed now. Make sure I'm up by nine. I slept through my alarm yesterday."


	5. Chapter 5

By the morning, John's blood sugar was down to 11.2, a number that John seemed relatively pleased with.

"I feel a lot better," he told Sherlock.

Sherlock had to admit, he looked a lot better. Less pale and exhausted.

He watched John go through the same routine he had the night before. This time it was accompanied by an insulin shot to his stomach before eating.

"It's one of the best spots," he explained to Sherlock, who was watching with fascination. "I can't use one site too often, or it won't absorb as well."

Sherlock nodded, soaking it all in.

John ate his breakfast like normal, but Sherlock kept watching him. John wasn't sure for what, because it wasn't like the insulin would announce its entrance with a flag or sign.

Perhaps he was taking mental notes for an experiment.

* * *

They went off to the appointment Sarah had set up.

The endocrinologist was a lovely man by the name of Doctor Edwards. He'd been treating patients as long as Sherlock had been living, and was the sort of man that demanded respect, simply on the basis of his knowledge. Sherlock was impressed.

He smiled as he read the charts Sarah had sent over, and continued to smile as John recounted the story.

"It's novel to have a patient as knowledgeable as you, Doctor Watson."

"John, please."

He nodded.

"And Mr Holmes?"

"Sherlock."

He nodded again.

"This will be a time filled with an enormous amount of changes, and even though you're aware of them, it won't be as easy as you are anticipating. It's going to be exhausting and annoying, and sometimes you're just going to want to throw in the towel. But you can't."

John nodded seriously while Sherlock frowned. _What sort of things are going to happen?_

"I see that Doctor Sawyer set you up with a tentative dosage schedule. How's that been working so far?"

* * *

Sherlock listened patiently as the pair of doctors talked for hours, going through things like diet, exercise, lifestyle, and illness. He stored all the information away in a newly constructed room next to John's space in his mind palace. He may have had to do some renovations, but he hardly needed to know when Mycroft's birthday was. This was by far more important.

* * *

Finally they were allowed to go, John with another stack of pamphlets and notes about diet and dosages, and Sherlock with a head too full of new information to comprehend much else at the moment. He needed time to sit down and regroup, which was why it took him so long to register that John was speaking to him.

"Sherlock!" John said exasperatedly, like he was repeating it for the tenth time, which was entirely possible.

"John," he replied.

"You're not listening. I said we should go get some lunch."

Sherlock glanced at his watch. It was indeed time for lunch. John needed to eat. And it wasn't a need to eat that could be ignored, because from everything he'd heard yesterday as well as today, John needed to maintain a fairly regular schedule to keep his blood sugar levels from fluctuating.

"Right. Where to?"

John shrugged.

"Angelo's is always good. And nearby."

Sherlock nodded, beckoning a taxi and given the driver the address. "Are you feeling alright?" he asked John once they were seated.

John laughed openly.

Sherlock was perplexed.

"Oh, don't be like that," John teased, noting the look on Sherlock's face. "It's just really amusing to me this sudden change in character. You're concerned. It's kind of nice."

"Of course I'm concerned," Sherlock huffed. "You are an important part of my work."

He finished the sentence there, but they both knew it wasn't complete.

_And life... _their minds both finished for them. Because it was true.

The rest of the cab ride was silent.

* * *

They were seated immediately, yet another perk of everyone owing Sherlock favours.

"Diet coke please Angelo," John told him.

"Tea," Sherlock muttered.

The man nodded and walked away.

Sherlock scrutinized John as he tested, finally holding the meter up for Sherlock to see. 6.9.

Sherlock grinned. "Almost normal!" he declared.

John smirked. "Yes, thank you for informing me. I really _wasn't _aware."

Sherlock only smirked back as Angelo returned to take their order.

* * *

Sherlock watched John carefully calculate the average number of carbohydrates in a dish that size, and inject the according amount of insulin.

"Is there a formula for that?" Sherlock asked.

John blinked at him. "Were you listening at all this morning?"

Sherlock scrolled through his memories, but couldn't find anything that looked mathematical.

"Yes," he said defensively. "I could recite the bit about importance of tight control and the history of the treatment."

John shook his head, his mouth full of pasta. "Don't wanna hear it," he mumbled.

"I couldn't memorize it all, John," he defended. "Don't be absurd."

John only shrugged and inhaled noodles like there was no tomorrow.

Sherlock was displeased when his hand was swatted away from John's plate to prevent him from stealing some noodles.

"Not until I get the hang of this," he threatened. "With my luck, and this soon, I would have taken too much insulin and would have a hypoglycemic episode."

Sherlock sighed dramatically, but relented, agreeing that it wasn't a good idea.


	6. Chapter 6

The first time John had an unexpected low was terrifying for both of them. Neither of them had seen it coming, and it didn't even have an obvious cause. They weren't in the middle of a chase, John hadn't been exercising, and he was well.

"Sherlock?" John had called.

Sherlock had been in the midst of an experiment studying bacterial cultures when John had called him.

"What?" he called back without looking up from his microscope, scribing notes with one hand while adjusting the view with the other.

"Sherlock," he said again, and there was something in his voice that made Sherlock abandon his cultures and look to his friend.

John was standing just across the island from him. _How did he get there without me hearing? _He seemed unsteady and pale, and despite being indoors on a relatively cool day, he was sweating.

"John, are you alright?"_ Of course he's not you idiot, _he scolded himself. He shook his head, as if to clear the question from the air.

"I could use some help," he said, looking down at his hand, which was shaking rather more that usual. And was bleeding. Feeling rather slow, Sherlock's brain made the connection between the blood on his finger and the waiting test strip below.

Sherlock carefully directed John's shaking finger to the tip of the strip, which greedily sucked back the blood and began to count down.

"Now sit down," he scolded, leading John from his spot at the counter to his chair. "You're obviously low. You should have started by eating something."

"Yeah," John conceded absentmindedly. He sank into the chair, his legs happy to be free of their burden.

Sherlock rolled his eyes at John and peered at the meter, which had since flashed the warning number, 2.6.

"Low," Sherlock declared, practically throwing the meter at John, who fumbled with it. He yanked the drawer that had been allocated for John's supplies, practically pulling it out of its spot, and retrieved a roll of glucose tabs. Stalking back over to John, he dropped two in his hand.

"Chew," he ordered.

John obeyed, grinning stupidly.

* * *

Half an hour later, when he was back in the acceptable range at 4.9, John smiled a weary thank you and declared it one of the most unnerving experiences in his life. Sherlock may have gone shopping after that, picking up glucose tabs in every known flavour, stuffing his pockets with them and hiding them in convenient places around the flat.

Including inside the skull.

* * *

John only went a few weeks before he decided he wanted to try a pump.

"It'll fit better with your lifestyle," he told Sherlock. "And therefore, mine."

Sherlock had only sniffed indignantly and trailed along after him when he announced he was leaving for the appointment.

* * *

If Sherlock thought the appointment the day after John's diagnosis was long, then this was eons. He was even more put out to find that it was only the first in a series of appointments John would require for 'training'.

"It's not a puppy," Sherlock grumbled on the way out, after hours and hours. "I don't see why they call it training."

John sighed wearily. "Sherlock, you're rather dense. I'm the one receiving the training. And I've told you that you don't have to come."

"I want to," he said petulantly.

"I know," John sighed.

* * *

They were more training sessions to go to, and true to his word, Sherlock accompanied John to all of them, even remaining relatively well behaved, although sometimes, he was moody to the point where the nurses would ask if he was feeling low. John always giggled at that as he explained he was the one there for training, rather than Sherlock.

* * *

When John did finally get the pump, Sherlock had to admit it was clever. Instead of shots, all John had to do was push some buttons. Much more convenient. Although he had to admit, the tiny tubing was a bit of a draw back, having gotten caught more that once on things in that flat, and that one time in the middle of a chase when it had been forcefully yanked from his skin, leaving a bleeding spot he hadn't noticed until he was back at home, crabby from the unexpected high.

Sherlock was partial to the idea of taping every inch of the tubing to John's skin, leaving no room for snags. John shot that idea down before Sherlock even finished saying it.

He pouted for the rest of the afternoon.


	7. Chapter 7

They'd told Mrs Hudson, not wanting her to expect the worst if she came across a needle one day. Besides that, Sherlock wanted her to know what to do in case of emergencies. She took it all rather in stride, seeming almost too enthusiastic about practising on the orange with the glucagon injection.

Mycroft had known, of course, probably even before John had figured it out, in that unnerving way he tended to know things.

To be honest, Sherlock had forgotten about Lestrade.

* * *

They were called to a crime scene, nothing too excited, maybe only a five, but they both needed to get out of the flat. John was moody, still suffering the effects of having been running high for the most of the previous day and night, and wasn't in the mood to put up with Sherlock blowing things up, making a mess, or running off.

"Sherlock, would you stop acting like a child!"

"I'm not," he retorted, sounding exactly like a five year old.

"You're acting like that kid you had to interview last week. Remember her?"

Sherlock scowled at the thought. "Yes, well at least I'm not high, thank you," he'd snapped.

"Sherlock?" Lestrade asked, eyes wide with incredulity. "What are you talking about?"

Sherlock ran over that sentence in his head. It probably didn't sound the best to an outsider.

"John, this one's all you," he declared, stalking off towards the body.

"John?" Lestrade asked, raising a solitary eyebrow. "Something you want to tell me?"

John grinned, pulling his pump out of his pocket to show it to the Detective Inspector. "Diabetic. Sherlock was referring to a high blood sugar rather than a drug high. Of course, he tends to make things sound the worst possible way they could."

Lestrade crossed his arms. "How come I'm only finding out now?"

John shrugged, slipping the pump back in his pocket. "To be honest, it never really came up. It's not like we spend much time standing around talking about anything other than how annoying Sherlock is being."

Lestrade nodded. "How long has it been?"

"About a month now."

"And how has Sherlock been about the whole thing?" Lestrade asked.

"Not bad," John replied. "It's been hard for him, because now I actually do have to eat, and sometimes I feel like crap just when he's ready to run off after a suspect or something. But after I had my first serious low a couple weeks ago, he ran out and bought what seems to be the entire stock of Tesco's glucose tabs." He grinned at the thought, recalling all the strange places he'd been discovering them lately. It was almost like a game.

Lestrade nodded. "I'd like to know more. Go out for a drink some time?"

John nodded, and pointed at Sherlock.

"I think you should probably interfere," he explained, watching Sherlock gesture angrily at Anderson, snatches of the conversation drifting over, none of it pleasant.

Lestrade set his face in a grim line and stomped over, bellowing louder than all of them to quit behaving like children.

John couldn't help but grin as he headed over behind him.


	8. Chapter 8

Sherlock, true to his word, had not touched any of John's supplies yet. But two months in, John on the pump and his blood sugar levels fairly steady, he figured it wouldn't hurt to do some experimenting.

It had started off harmless, just testing his blood sugar with the bonus meter John had gotten, muttering something about chases and Sherlock dragging him off without giving him a chance to grab everything. So now John had a tiny meter that lived in his coat, and the normal one he used most of the time. That was all well and good, but his interest in that didn't last long. It wasn't as if Sherlock's blood sugar was changing all that much, his pancreas doing what John's couldn't, however dull the task may be.

Until he had the realization that it could change, under the right circumstances.

There was an entire section of his brain screaming at him that this was a bad idea, but he ignored it in favour of the fascinated section, which urged him to do it.

He'd calculated the dosage carefully, one that would dip him into the low range, but only barely.

Sherlock was perched on the couch, the meter sitting on the table in front of him, along with an army of glucose tabs, and the orange glucagon kit, just in case.

He checked the text from John, sent seven minutes ago, stating he would be home in ten.

It was now or never.

Sherlock took a deep breath and plunged the needle into his abdomen where he'd wiped it with an alcohol wipe. It wasn't the needle that scared him, he'd had enough of those to last a lifetime, but it was the effect that the contents of the needle would have on him that he was worried about.

After all, John, the man who'd been shot in a war, then come home to London, only to be stabbed, strangled, and shot again, had claimed a low was the most unnerving experience of his life.

He recapped the syringe, with fingers that were already beginning to tremble, whether that was an actual symptom or simply psychosomatic at this stage was hard to tell.

He focused on putting a test strip into the meter, pulling the device closer. As he pricked his finger, he noticed a definite tremble, a real one. It made it hard to hold his finger steady and direct the droplet of blood towards the tiny target. He made a note to look into that.

While he waited for it to count down, he absentmindedly wiped the leftover blood from his finger on the couch, only belatedly thinking that was probably a bad idea, but his mind was foggy, and obviously not thinking clearly at the moment.

The meter flashed a 3.2, and Sherlock looked at it for a moment, marvelling at the magic. But then the rational part of his brain (the one that told him not to do this experiment) yelled at him that he had to do something about it, and Sherlock had to admit it was probably right.

He reached for the glucose tabs, cursing their packaging, and made a note to look into those as well. He shoved one in his mouth, crunching hard, the taste of chalk filling his mouth. He made another note to make them taste better, somehow. He finished one, and shoved another one in his mouth, the distant sounds of a cab door slamming and the front door opening. John was home.

Sherlock's brain, the entirety of it, panicked, clumsily shoving evidence under couch cushions. How had he not prepared for this eventuality? _Stupid, stupid, stupid, _he cursed himself.

He lay back on the couch in his thinking position just as John came in the door, surveying the room suspiciously.

"What are you doing Sherlock?"

"Thinking," he replied, working hard to not slur the words around the chalky flavour in his mouth.

John shook his head and went into the kitchen, flipping the kettle on.

"Tea?"

Sherlock hummed in response.

John sighed and reached into the fridge for the milk, finding instead the insulin bottle that Sherlock had taken his sample from. It had moved. Slightly.

_Damn._

John returned to the living room, holding the bottle in his hand."Sherlock, have you been experimenting with the insulin?"

"Of course not," he scoffed, hoping it sounded convincing.

John scrutinized him. "Liar. You're paler than usual and despite trying to hide it, you're trembling." He raised an eyebrow. "Unless, of course, it's psychosomatic."

"Of course it's not," he snapped.

John threw two more glucose tabs at Sherlock. "Chew," he ordered, digging the meter out from the cushion, instinctively knowing it was hidden there. "Hand," he demanded, brandishing the lancing device like a weapon.

Sherlock frowned, but flung an arm at him, not even blinking as John attacking his finger, possibly with more force than necessary, squeezing a droplet of blood onto the strip. It was easier to do with steady hands, and John's were. _(Under pressure right now...) _

"What was it before?"

"3.2," Sherlock replied, not even bothering to ask how John knew he'd tested recently.

John nodded. "Headed in the right direction." He held the meter up for Sherlock to see, 3.6. "I'll get that tea."

Sherlock nodded, just laying there on the couch, feeling rather like crap, and understanding why John wished to avoid these. They sucked. And to top it all off, he could feel a headache coming on, one that he suspected he'd been unable to get rid of that day. Just punishment, perhaps.

John returned with the tea, and Sherlock could tell it was sweeter than usual. "Don't," John warned.

Sherlock didn't.

After the tea, John grabbed a different finger an attacked it, seeming content that the number was up to 4.5. That was when he sat down on the table to scold Sherlock.

"You are a daft bastard," John had told him, his voice steady. That was perhaps the most terrifying part, that he wasn't yelling, or even raising his voice, but was perfectly calm.

"I just wanted to know what it was like..." he whispered.

"Why could you want to experience that?" John sounded completely outraged.

Sherlock was silent. He could see John thinking that over, and it was like a light bulb went on. John's thinking really was that obvious.

"Oh..." he said faintly. "Sherlock..." he trailed off. "I appreciate the thought, but it's really not necessary. And that was stupid, doing it like that, alone."

"You're often alone," he pointed out.

John sighed. "Yes, but I don't have a choice. You do, and you made a pretty stupid one."

Sherlock pouted.

"But I know how your big stupid brain works, so I get why you did it. I'm just saying, don't ever do it again. I have enough to worry about without stressing over whether you're shooting up insulin at home in the living room to see what it feels like."

"Fine," Sherlock conceded.

He knew what it was like now, and as far as he was concerned, would be fine if he never experienced it again for the rest of his life.

* * *

Life went on. It was the same as life before, except there was more eating, the occasional blood droplet on furniture, and chalky glucose tabs thrust at you from every angle when you finally managed to say "I feel low". Of course it wasn't easy, but nothing ever was.

Especially when Sherlock was around. But to everyone's shock, he was more understanding than impatient, more protective than dismissive, and was the first to suggest that perhaps John was feeling low when he couldn't see that the dead woman was strangled, not shot.

And in John's books, that was a caring Sherlock.


End file.
